Defensive Tackle Geno Atkins, Bengals

NBC Sports' Midseason All-Pro team elected to use a 3-4 defense with undersized Atkins as its lone interior lineman. Although he's generously listed at 6-foot-1, 300, Atkins has mastered the art of the double-team split with a ferociously fast first step and quick-twitch up-field pass-rush ability. Not a liability against the run, Atkins routinely knifes through offensive lines for tackles for loss and leads his position in sacks (7) through eight games. Atkins is the league's best defensive tackle.

Defensive End Cameron Wake, Dolphins

One of the league's most disruptive 3-4 outside 'backers the past two years, Wake transitioned to 4-3 defensive end this season and hasn't missed a beat. Wake sees action primarily at left end in rookie coordinator Kevin Coyle's scheme and has an even greater in-game impact than his 8.5 sacks suggest. Wake is a quarterback hurry waiting to happen and stuffs the run on early downs.

Linebacker Clay Matthews, Packers

Mathews has switched from strong- to weak-side rusher in Green Bay's 3-4 defense this year, and his production has taken off. Finishing last season with just 6.0 sacks, Matthews already has nine in 2012 as the captain of a Packers defense that leads the NFL in that category. When Matthews isn't pounding signal callers into the turf, he's drawing double teams to make things easier on his teammates. He can rush with speed and power, and controls the edge in early-down run defense.

Linebacker Daryl Washington, Cardinals

A backfield penetrator from the second level, Washington is the lynchpin of Arizona's interior defense as a fire-zone blitzer and steady presence against the run. With eight sacks through nine games, Washington will become the first NFL inside linebacker to record double-digit quarterback takedowns since 2001 (Charlie Clemons, Saints). Washington also ranks in the top five in tackles, and leads the league in solo stops. He has eye-catching speed and plays sideline to sideline.

Linebacker Patrick Willis, 49ers

Willis earned five Pro Bowl trips and four First-Team All-Pro honors in his first five NFL seasons. Barring something unforeseen, he'll pad those accolades in 2012. A clock-cleaning hitter who's relentless in pursuit, Willis is on pace for 130 tackles and four turnovers forced. He also excels in pass coverage, where Willis has batted down six opposing quarterbacks' throws. The Niners rank top five in total defense, pass defense, and run defense, and Willis is their defensive centerpiece.

Linebacker Von Miller, Broncos

Ripping through and past offensive linemen like a rolling ball of butcher knives, Miller has built on his Defensive Rookie of the Year campaign with a truly dominant first half of his second season. A "joker" and movable chess piece in John Fox's 4-3 defense, Miller plays both end positions and strong-side linebacker, and can rush from the interior in a pinch. Only J.J. Watt has more sacks this year, and no outside rusher bends the edge or explodes off the snap as furiously as Miller.

Cornerback Charles Tillman, Bears

"Peanut" is 31 years old, but he's got plenty of juice left in his tank. He shut down Calvin Johnson (three catches, 34 yards) in Week 7, and for the most part offenses simply opt against testing Tillman's side of the field. A ball-stripping takeaway specialist, Tillman has forced an otherworldly seven fumbles and intercepted two passes, returning both to the house. The Bears lead the league with a plus-16 turnover ratio, and Tillman keys the back end of the NFL's best defense.

Cornerback Antonio Cromartie, Jets

Many observers expected the Jets' defense to collapse after Darrelle Revis' Week 3 ACL tear. Not quite. Rex Ryan's team doesn't win much, but it can still eliminate its opponent's top receiver. Playing the most smothering coverage of an up-and-down career, Cromartie is the primary reason New York has held opposing No. 1 wideouts out of the end zone in all of its games since Revis' injury. Despite losing their best pass defender, the Jets are still playing top-six pass defense.

Safety Reshad Jones, Dolphins

Jones' box-score numbers don't jump off the page (two interceptions, 43 tackles, seven pass breakups, one forced fumble), but he is a rangy back-half cover man who consistently shows up in run support, knifing into backfields from his strong safety spot. 24 years old and in his second season as a starter, Jones is enjoying a breakout year and his best football is still ahead of him.

Safety Jairus Byrd, Bills

On pace for career highs in tackles (84), pass breakups (12), and forced fumbles (six), Byrd is a ball-hawking safety with multi-dimensional impact. Byrd can cover center field, match up one-on-one with tight ends, and hold his own against the run. An increasingly complete safety brimming with playmaking ability, Byrd has been the lone bright spot on an underachieving Bills defense.